The use of research animals in research has been essential to development of vaccines and study of most human diseases. Modern rodent research is increasingly powerful with the ability to manipulate the genomes of mice and rats such that they closely mimic complex human diseases such as Alzheimer's and artherosclerosis. Generating transgenic mice and rats, requires that embryos that are manipulated by researchers be transferred into recipient female mice where they can complete their development. Up to this point, these transfers have required surgical procedures in which the embryo is implanted into the uterus. Recently, a device has been developed that enables these embryo transfers to be performed without surgery which eliminates the post-operative recovery period thereby reducing pain of the animals. This proposal investigates and expands upon the utility of this embryo transfer device by establishing the optimal ages and mouse strains for embryo transfer (Aim 1), determining whether embryonic stem cells can be effectively and efficiently transferred with this device (Aim 2), determining whether the device is useful for artificial inseminations (Aim 3), directly visualizing the device in the uterus which may enable design improvements (Aim 4) and quantifying measures of stress relative to surgical procedures to support widespread adoption of this procedure in the research community (Aim 5). The primary project objective is to produce data that will prove the efficacy of this embryo transfer device and thereby enable researchers to replace surgical procedures with a non-surgical method that is equally effective. Proving that this non-surgical transfer method is effective under a range of conditions will expand its use over this range of applications and thereby maximize its impact in enabling researchers to refine and reduce the number of surgical procedures performed in mice. PUBLIC HEALTH RELEVANCE: Animal use in research is essential for biomedical research and with the developing abilities to genetically engineer mice for research; these animals are becoming even more important as they can be modified to mimic most human diseases. Genetic engineering of mice requires, as one of many other things, the ability to transfer embryos into mice where they complete their development. This project supports further development of a device that enables these embryo transfers to be performed without surgery and therefore greatly reduces the pain category that these research animals experience and thereby supports progress in biomedicine.